The present invention is directed to a dental x-ray diagnostic installation or apparatus for producing congruent panorama strip exposures of the jaw of a patient. The apparatus includes a rotary unit, which carries a radiation source and a film cassette and has at least two positioning members for positioning the patient's head with reference to the rotary unit. One of these positioning members is a forehead support adjustable in a horizontal direction and the device or apparatus includes a display arrangement for indicating at least the adjusted position of the forehead support.
In a known x-ray diagnostic installation or apparatus, an example is disclosed in the sales brochure for ORTHOPANTOMOGRAPH a forehead support for positioning the patient's head on one hand, and also a chin support with a bite-down part are provided. Chin supports and forehead supports are horizontally adjustable in the direction towards a pillar or stand on which the rotary unit comprising the x-ray source and a film cassette are pivotably mounted. In order to be able to correctly position the patient's head with reference to the centricity and inclination (Frankfurter Horizontal), a light beam localizer or positioner is also provided so that the correct inclination of the skull on the one hand, and also the center of the face are capable of being set or, respectively, monitored with the light beam localizer. The patient position, which has been set, can be read from a digital display.
Both what is referred to as a standard exposure, for example exposures of the upper jaw and lower jaw, as well as what is referred to as sine exposures, for example exposures of the superior maxillary cavities as well as exposures of the maxillary joint, can be produced with such an apparatus. The adjustably arranged chin support is provided with a small, pivotable retaining rod or with a bite-down part for fixing the front teeth of the jaw. Even though it is possible to produce reproducible exposures with the apparatus set forth because the values of the forehead support position and those of the position of the chin position have been recorded or noted and these values are then re-set when another exposure of the same patient is to be made, the adjustment precision obtainable with this apparatus nonetheless does not correspond to today's demands with respect to a deviation of less than 1 mm for the later exposure with respect to the original exposure.
Such precise reproducible exposures cannot be achieved with other apparatuses which have been disclosed in a patent literature, for example U.S. Pat. No. 2,720,708 and German patent No. 898,793. These are affected by even a further disadvantage because the adjustment of the patient's head is relatively time consuming and complicated. For example, in the device of the German patent No. 898,793, four positioning members must be adjusted. The apparatus contains an annular shackle on which two pins are located for introduction into the orifices of the auditory passages. The shackle also adjustably supports a slide part, which can be applied to the transition between the upper lip and the lower root of the nasal septum. Also mounted in the shackle is an indicator pin in which the point of entry of the x-ray can be marked on the patient's skin by means of a colored dot. The shackle and the four positioning members or, respectively, their mounts are provided with scales in the form of line markings which must be read and noted after the patient has been adjusted.
In the apparatus of U.S. Pat. No. 2,720,708, which is not able to make panorama strip exposures of the jaw of a patient, first and second positioning members are provided with the first being a bite-down part for the front teeth and the second being a cap which can be placed on the patient's head. These positioning members are suspended in an adjustable fashion in a number of planes and each of the adjustment elements is provided with scales.
The two known apparatuses offer no possibility of carrying out initially cited different types of exposures, for example lower jaw, upper jaw, sinus and maxillary joint exposures for either a patient with teeth or for a patient who is without teeth.